I wonder if anyone knows of a project or kit that uses a 'scope
timebase output as the basis of an HF spectrum analyser. My aim is
to make something that would be useful for filter work so I'm not
necessarily looking for very wide frequency sweep.

TIA,


Charlie.

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www.radiowymsey.org

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"M0WYM" wrote in message
...
I wonder if anyone knows of a project or kit that uses a 'scope timebase
output as the basis of an HF spectrum analyser. My aim is to make something
that would be useful for filter work so I'm not necessarily looking for
very wide frequency sweep.
Charlie. M0WYM


My own analyzer was a kit for a QST project sold by
A&A Engineering; the design centered around a CATV
module and had it's own timebase and IF strip/log detector
internally. The analyzer used the scope as a X-Y display.
For serious SSB and CW filter work the VCO is going to
be tricky, you'll need low phase noise, etc.; and a good
set of narrow IF filters that can be swept is another
can of worms. Most of the ham analyzers are better
suited for wider IF responses and wide sweep ranges.
I did a major rework of the IF and Log Amp using an
Analog Devices chip, but the analyzer still has
limitations.

I'd seriously look at some of the DSP receiver kits that
are now on the market--most offer spectrum display
on the computer screen, and adding a good, but
simple, sweep generator might be an easier approach.

Pete

Tio Pedro wrote:
SNIP

I'd seriously look at some of the DSP receiver kits that
are now on the market--most offer spectrum display
on the computer screen, and adding a good, but
simple, sweep generator might be an easier approach.

Pete



Pete,

That does sound interesting and pretty inexpensive. You have me
thinking now


Thanks,


Charlie.

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On Dec 30 2008, 9:41*am, "Tio Pedro" wrote:
"M0WYM" wrote in message

...

I wonder if anyone knows of a project or kit that uses a 'scope timebase
output as the basis of an HF spectrum analyser. My aim is to make something
that would be useful for filter work so I'm not necessarily looking for
very wide frequency sweep.
* Charlie. M0WYM

My own analyzer was a kit for a QST project sold by
A&A Engineering; the design centered around a CATV
module and had it's own timebase and IF strip/log detector
internally. The analyzer used the scope as a X-Y display.
For serious SSB and CW filter work the VCO is going to
be tricky, you'll need low phase noise, etc.; and a good
set of narrow IF filters that can be swept is another
can of worms. *Most of the ham analyzers are better
suited for wider IF responses and wide sweep ranges.
I did a major rework of the IF and Log Amp using an
Analog Devices chip, but the analyzer still has
limitations.

I'd seriously look at some of the DSP receiver kits that
are now on the market--most offer spectrum display
on the computer screen, and adding a good, but
simple, sweep generator might be an easier approach.

Pete

I had a little one band kit radio that was varactor tuned in my hands
for a while and used the sweep voltage from a scope to to drive the
varactors. I was interesting but the scope didnt have enogh
persistence to show a good display. It really looked cool when you
used a marker generator with it in a dark room.

JImmie

JIMMIE wrote:
SNIP

I had a little one band kit radio that was varactor tuned in my hands
for a while and used the sweep voltage from a scope to to drive the
varactors. I was interesting but the scope didnt have enogh
persistence to show a good display. It really looked cool when you
used a marker generator with it in a dark room.

JImmie


Jimmie,

That sounds like fun - I will have to try that with my BITX20A which
I modding to varactor tuning

Charlie.


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On Jan 2, 5:16 am, M0WYM wrote:
JIMMIE wrote:

SNIP



I had a little one band kit radio that was varactor tuned in my hands
for a while and used the sweep voltage from a scope to to drive the
varactors. I was interesting but the scope didnt have enogh
persistence to show a good display. It really looked cool when you
used a marker generator with it in a dark room.

JImmie

Jimmie,

That sounds like fun - I will have to try that with my BITX20A which
I modding to varactor tuning

Charlie.

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Sign today!http://petitions.pm.gov.uk/SaveShortwave/

Hey OM
You'll have to find that sweet spot for the ramp sweep frequency,
depends on the bandwidth of the scope or the persistence of the crt.
The sweep bandwidth depends on the varactor tuning voltage, not on
the frequency. So you have to adjust the peak voltage of the ramp to
adjust the bandwidth. On the scope where X input is your ramp voltage
and Y input is the detected output of the tuner, with the sweep on the
scope turned off. The resolution will depend on the input bandwidth of
the tuner.

73 OM
n8zu

"M0WYM" wrote in message
...
I wonder if anyone knows of a project or kit that uses a 'scope timebase
output as the basis of an HF spectrum analyser. My aim is to make something
that would be useful for filter work so I'm not necessarily looking for
very wide frequency sweep.

TIA,


Charlie.

Hi Charlie,
For very little money, you can buy the miniVNA:
http://www.miniradiosolutions.com/

That will far outplay anything you can build. Because it makes use of a PC,
it will have features well beyond a simple SA + tracking generator. In
addition, it's a vector device.

GL,
Dale W4OP

"Dale Parfitt" wrote in message news:ZCq6l.1994$
Hi Charlie,
For very little money, you can buy the miniVNA:
http://www.miniradiosolutions.com/

That will far outplay anything you can build. Because it makes use of a
PC, it will have features well beyond a simple SA + tracking generator. In
addition, it's a vector device.

GL,
Dale W4OP


Their scalar network analyzer looks awesome too!
There's an amazing lack of "boatanchor" hardware
in these devices.

"Tio Pedro" wrote in message
...

"Dale Parfitt" wrote in message news:ZCq6l.1994$
Hi Charlie,
For very little money, you can buy the miniVNA:
http://www.miniradiosolutions.com/

That will far outplay anything you can build. Because it makes use of a
PC, it will have features well beyond a simple SA + tracking generator.
In addition, it's a vector device.

GL,
Dale W4OP


Their scalar network analyzer looks awesome too!
There's an amazing lack of "boatanchor" hardware
in these devices.
Not even any condensers.

Dale

Dale Parfitt wrote:
SNIP
For very little money, you can buy the miniVNA:
http://www.miniradiosolutions.com/

That will far outplay anything you can build. Because it makes use of a PC,
it will have features well beyond a simple SA + tracking generator. In
addition, it's a vector device.

GL,
Dale W4OP


Dale,

That is neat but it works out as over £200 here (around $300). I
will bear it in mind as it would be great for antenna work using a
laptop.

Thanks,


Charlie.

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http://petitions.pm.gov.uk/SaveShortwave/